1. Field of the Invention
This invention relates to an automobile weather strip that is attached to a rim of an opening of a vehicle body of an automobile for sealing between the vehicle body opening rim and an opening open/close member. Particularly, this invention relates to an automobile weather strip having a trim part to be attached to a flange part formed on the vehicle body opening rim or the opening open/close member and a sealing part for contacting the opening open/close member or the vehicle body opening rim for sealing.
This invention will be described by taking as an example an opening trim weather strip that is attached to a flange part of a rim of an opening of a vehicle body and brought into contact with a door for sealing between the door and the vehicle body when the door of the automobile is closed.
2. Related Art
As shown in FIG. 4, an opening trim weather strip 110 attached to a vehicle body opening rim 6 of an automobile is molded by extrusion molding and formed of a trim part 120, a cover lip 130, and a hollow sealing part 140.
The trim part 120 has a substantially U-shaped section and holds a flange part 9 formed on the vehicle body opening rim 6 so that the opening trim weather strip 110 is attached to a whole periphery of a vehicle body opening. The trim part 120 has an insert member 126 that is embedded thereinside, and a vehicle exterior side holding lip 124 and a vehicle interior side holding lip 125 for holding the flange part 9 are formed on an inner surface of the substantially U-shaped section, so that the trim part is held at the flange part 9 of the vehicle body 1 by the holding lips 124 and 125.
The hollow sealing part 140 is integrally formed on an outer surface of a vehicle exterior side of the trim part 120, so that the hollow sealing part 140 contacts an outer periphery of the door 2 when the door is closed, thereby sealing between the door 2 and the vehicle body opening rim 6. The hollow sealing part 140 is formed from a sponge material in order that the hollow sealing part 140 flexibly contacts and reliably seals the door 2 in accordance with the shape of the door 2. In general, an EPDM sponge rubber having a specific gravity of 0.4 to 0.6 and a 25%-stretching stress of 140 to 190 KPa has been used as this sponge material in view of flexibility, resistance weather, strechability, and rigidity. When the specific gravity is less than 0.4, a predetermined rigidity (25%-stretching stress) is not achieved to make it difficult to achieve a sealing pressure when the door is closed and to raise the risk of unnecessary deformation when attached as being curved along a corner part of the vehicle body opening rim 6. In turn, when the specific gravity is more than 0.6, the rigidity is increased to cause a drawback of an increase in door closing force.
The cover lip 130 is extended in a vehicle interior side direction from an outer surface of a vehicle interior side of the trim part 120 and contacts a garnish or the like provided on a car interior to cover a gap between the opening trim weather strip 110 and the garnish and the vehicle body. A surface layer 133 made from a thermoplastic elastomer which is a solid material is provided on a surface of the cover lip 130 for decoration purpose.
In such opening trim weather strip 110, the trim part 120 has the insert member 126 that is embedded thereinside and the vehicle exterior side holding lip 124 and the vehicle interior side holding lip 125 in order to reliably hold the flange part 9, and the solid material of an EPDM rubber has been used as a material for covering the insert member 126. The solid material of the EPDM rubber has a specific gravity of about 1.2 to about 1.3 and a 25%-stretching stress of 800 KPa or more, thereby achieving a sufficient rigidity. Therefore, the trim part 120 made from the solid material of the EPDM rubber holds the flange part 9 with the vehicle exterior side holding lip 124 and the vehicle interior side holding lip 125 to stably maintain the attachment posture.
However, due to the recent global environment protection, there is a demand for a weight reduction of automobiles, and, since a weight reduction in the opening trim weather strip 110 and the like has been required, the reduction has been achieved by finely foaming the solid material (see JP-U-57-153050, JP-A-11-193335, JP-A-2000-264135 and JP-A-2002-316537, for example).
However, the finely foamed solid material has a specific gravity of about 0.8 to about 1.05, which is insufficient for the weight reduction purpose when compared with the specific gravity (about 0.4 to 0.6) of ordinary sponge materials. The fine foaming was adopted since rigidity of the vehicle exterior side holding lip 124 and the vehicle interior side holding lip 125 are reduced too much (25%-stretching stress of 140 to 190 KPa) when a foaming ratio of the material used as the covering material is increased from the solid material (specific gravity: 1.2 to 1.3) to the ordinary sponge materials (specific gravity: 0.4 to 0.6) to make the trim part 120 to subject to falling from the flange part 9 due to a reduction in falling load caused by a reduction in holding force by the vehicle exterior side holding lip 124 and the vehicle interior side holding lip 125 when the trim part 120 is attached to the flange part 9 at an upper side of the door opening rim, and since there is the risk of failing to ensure the sealing property due to displacement of the hollow sealing part 140 that can be caused by inclination of the trim part 120 occurring when attaching the opening trim weather strip 110 while bending the opening trim weather strip 110 along the corner part of the door opening rim.
In order to ensure the rigidity of the vehicle exterior side holding lip 124 and the vehicle interior side holding lip 125, a thickness of the vehicle exterior side holding lip 124 and the vehicle interior side holding lip 125 may be increased. However, there is a limit for the increase in thickness since an inner part of the substantially U-shaped section of the trim part 120 is narrow. In the case of forming the vehicle exterior side holding lip 124 and the vehicle interior side holding lip 125 from the ordinary sponge material, it is necessary to increase the thickness (about 1.0 to 1.5 mm) to a thickness that is twice the thickness or more in order to attain rigidity equivalent to the solid material or the finely foamed material, and such thickness increase has not been practical.
Also, a 25%-stretching stress achieved by keeping the thickness of the vehicle exterior side holding lip 124 and the vehicle interior side holding lip 125 to that of the conventional example and adjusting the specific gravity to 0.6 to 0.8 by adding a larger amount of a foaming agent to the finely foamed material is 200 KPa to 350 KPa which is equal to or less than a half of the specific gravity (0.8 to 1.05) of the conventional finely foamed material, thereby failing to exhibit the function as the trim part 120.
As described above, since the solid material forming the trim part 120 has the specific gravity of about 1.2, and since the finely foamed material has the specific gravity of about 0.8 to about 1.05, there is a demand for a reduction in specific gravity (to about 0.5 to about 0.8) by further foaming the materials.
However, though the reduction in specific gravity that is achieved by further foaming the finely foamed martial as described above is preferable in terms of the demand for lightweight, the rigidity is undesirably reduced to prevent the function of the trim part 120 serving as an attachment part from being exhibited.
Therefore, there has been a demand for an automobile weather strip that is further reduced in weight; ensures rigidity without a major change in outer shape of the vehicle exterior side holding lip 124 and the vehicle interior side holding lip 125; hardly or never comes off from the flange part 9; is capable of maintaining an attachment posture of the trim part; and is produced easily at a low cost.
In order to solve the above-described problems, the first aspect of the invention provides an automobile weather strip to be attached to a rim of an opening of a vehicle body of an automobile for sealing between the vehicle body opening rim and an opening open/close member, comprising: a trim part holding the weather strip as being attached to a flange part of the vehicle body opening rim or the opening open/close member and having a substantially U-shaped section and a sealing part formed integrally with an outer surface of the trim part and sealing as contacting the opening open/close member or the opening rim, wherein the trim part comprises an insert member and a covering material for covering the insert member and forms on an inner surface of the substantially U-shaped section a holding lip for holding the flange part;
the covering member is formed by using a sponge material of a rubber formed by using a blend material of an EPDM rubber and an olefin-based thermoplastic synthetic resin and having physical properties of a specific gravity of 0.6 to 0.8 and a 25%-stretching stress of 500 KPa or more; and
the sealing part is formed by using a sponge material of a rubber formed by using the EPDM rubber and not containing the olefin-based thermoplastic synthetic resin and having physical properties of a specific gravity of 0.4 to 0.6 and a 25%-stretching stress of 200 KPa or less.
According to the first aspect of the invention, the automobile weather strip has a trim part holding the weather strip as being attached to a flange part of a vehicle body opening rim or an opening open/close member and having a substantially U-shaped section and a sealing part formed integrally with an outer surface of the trim part as projecting from the outer surface and sealing as contacting the opening open/close member or the opening rim. Therefore, when the trim part is attached to the flange part of the vehicle body opening rim or the opening open/close member, the sealing part reliably contacts the opening open/close member or the vehicle body opening rim to seal between the vehicle body opening rim and the opening open/close member.
The trim part has an insert member inside thereof and a covering material for covering the insert member. Also, the covering member of the trim part forms on an inner surface of the substantially U-shaped section a holding lip for holding the flange part. Therefore, an outer shape of the trim part is maintained by the insert member, and a force of the vehicle body or the like for holding the flange part is increased, thereby achieving reliable attachment of the weather strip. Also, since the insert member is covered with the covering material, an appearance is improved, and the insert member is prevented from being corroded.
For the covering member, a sponge material of a rubber obtained by using a blend material of an EPDM rubber and an olefin-based thermoplastic synthetic resin and having physical properties of a specific gravity of 0.6 to 0.8 and a 25%-stretching stress of 500 KPa or more is used. Therefore, it is possible to reduce a weight of the trim part of the weather strip, and the holding lip formed on the inner surface of the substantially U-shaped section of the trim part has sufficient rigidity to increase a falling load of the trim part, thereby making it possible for the trim part to reliably hold the flange part.
The sponge material of the rubber is the blend material of the EPDM rubber and the olefin-based thermoplastic synthetic resin, and the rigidity is improved by blending the olefin-based thermoplastic synthetic resin and/or increasing a crosslink density of the EPDM rubber. Therefore, it is possible to maintain the shape without largely changing the outer shape of the holding lip as well as to keep sufficient rigidity for holding the flange part.
It is possible to adjust elasticity and rigidity by adjusting a blending ratio of the olefin-based thermoplastic synthetic resin. Therefore, the holding lip has an appropriate flexibility (elasticity) and is capable of maintaining a holding force by a flexure of the holding lip even when a thickness of the flange is changed as well as of reliably holding the flange part in response to unevenness and bending of the flange part.
The sealing part is formed by using a sponge material of a rubber obtained by using the EPDM rubber free from the olefin-based thermoplastic synthetic resin and having physical properties of a specific gravity of 0.4 to 0.6 and a 25%-stretching stress of 200 KPa or less. Therefore, the weight of the sealing part is reduced, thereby making it possible to reduce the weight of the weather strip as a whole.
Also, since the sponge material having the physical property of 25%-stretching stress of 200 KPa or less, the sealing part is excellent in flexibility, so that the sealing part is capable of reliable sealing as being deformed in accordance with the shape of a counter member when the sealing part contacts the counter member as well as of suppressing an increase in door closing force.
The second aspect of the invention provides the automobile weather strip, wherein the trim part comprises a cover lip that is formed integrally with the outer surface of the trim part as extending toward a vehicle interior side; and the cover lip is formed from the sponge material of the rubber that is the blend material of the EPDM rubber and the olefin-based thermoplastic synthetic resin.
According to the second aspect of the invention, since the cover lip is integrally formed with the trim part, and since the sponge material of the rubber that is the blend material of the EPDM rubber and the olefin-based thermoplastic resin and same as that used for the covering material of the trim part is used as a material for forming the cover lip, the cover lip covers between the weather strip and an interior member or a garnish and the like of the vehicle body to improve an appearance.
Also, since the cover lip is formed by the sponge material of the rubber, a weight of a part of the cover lip is reduced to contribute to the reduction in weight of automobile.
Further, since the sponge material of the rubber is the blend material of the EPDM rubber and the olefin-based thermoplastic resin that is the same as that used for the covering material, it is possible to improve rigidity by blending the synthetic resin and/or increasing a crosslink density of the EPDM rubber, and it is possible to adjust elasticity and rigidity by adjusting a blending ratio. Therefore, though the cover lip has the shape of the lip, the cover lip maintains the shape as well as to keep a sufficient contact force in contacting a counter member such as the garnish.
The third aspect of the invention provides an automobile weather strip wherein the sealing part has a hollow shape.
According to the third aspect of the invention, since the sealing part has a hollow shape, the sealing part is easily deformed as contacting the door that is the opening open/close member or the vehicle body opening rim when closing the door and reliably contacts unevenness and a curved surface of the door and the vehicle body opening rim. Also, the sealing part is not abnormally deformed when the door is closed as compared to those having a lip-like shape and capable of sealing even when there is a dimensional fluctuation in the vehicle body or the door.
The fourth aspect of the invention provides an automobile weather strip wherein outer surfaces of the sealing part and an outer surface of the cover lip are covered with a solid material.
According to the fourth aspect of the invention, since the sealing part and the outer surface of the cover lip are covered with the solid material, a surface is smooth, and appearance is improved. Since the sealing part has an inner part that is formed from the sponge material of the rubber having physical properties of a specific gravity of 0.4 to 0.6 and a 25%-stretching stress of 200 KPa or less, a weight of the sealing part is reduced, thereby making it possible to reduce the weight of the weather strip as a whole. However, since the inner part is formed from the sponge material, unevenness caused by foaming is caused on its outer surface. In order to diminish the unevenness and to improve wear resistance of the surface, the sealing part is covered with the solid material. Likewise, since an inner part of the cover lip is formed from the sponge material, unevenness caused by foaming occurs on its outer surface. In order to diminish the unevenness and to improve wear resistance of the surface, the cover lip is covered with a solid material of a thermoplastic elastomer.
Since the covering material forms on the inner surface of the substantially U-shaped section of the trim part the holding lip holding the flange part, the flange part is reliably held by the holding lip, and it is possible to reliably hold the flange part in response to unevenness and bending of the flange part.
Since the blend material of the EPDM rubber and the olefin-based thermoplastic synthetic resin is used as the covering material, and since the sponge material having physical properties of a specific gravity of 0.6 to 0.8 and a 25%-stretching stress of 500 KPa or more is used, it is possible to reduce the weight of the trim part of the weather strip as well as to maintain the sufficient rigidity of the holding lip, thereby making it possible to reliably hold the flange part with the trim part.